Tolerance rings constrain movement between parts that move relative to each other, such as rotating shafts in housing bores. One type of tolerance ring is an annular band located in the gap between the outer surface of a shaft and the inner surface of a bore. This tolerance ring limits radial or axial motion of the shaft within the bore while still permitting relative movement.
In conventional tolerance ring configurations, a close fit is sought between the inner and outer components. In addition, either forces for providing maximal frictional engagement or minimal variation in sliding forces are sought. A close fit between the components is desirable because it reduces relative vibration between the parts. Thus, tolerance rings are able to compensate for tolerances or misalignments, create torque and can improve other properties, such as noise, vibration and harshness (NVH) properties. Torque and even NVH are mainly influenced by the material properties of common tolerance rings, which are usually formed only from stainless steel. These requirements between the inner and outer components require strong and substantial contact, which increases frictional forces. Although these solutions are workable for some applications, improvements in tolerance rings continue to be of interest.